It is often necessary or convenient to clean the inside walls of fluid-filled tanks from the outsides of such tanks, thereby wholly avoiding the need for the cleaning personnel to enter the fluid-filled tank. While this task is frequently encountered in largescale industrial tanks in the food, chemical, drug, and other industries, the task's difficulties may be better grasped if considered in more common surroundings, such as the task of cleaning a home aquarium tank. Aquariums are designed to host aquatic life in a natural and attractive manner. Maintaining an attractive aquarium requires regular care and cleaning to achieve this goal. The walls of aquariums accumulate algae, including hard coralline algae, and this needs to be removed with the least amount of disturbance to the aquarium's inhabitants to maintain an attractive view. Current cleaning apparata which use razor blades to remove algae can be dangerous for the aquatic life within the aquarium (as well as for the user).